Knives, Hatchets & Multi-Plane Parts

All customer-supplied blade and axe work is high-stakes irreversible work. Read the Disclaimer & Liability module before starting.

Most premium engrave projects aren't flat sheets of stainless. They're knives, hatchets, hunting axes, custom kitchen tools, pieces with multiple surfaces, curved blades, and customers expecting different finishes on different parts of the same object. Here's how to handle it.

The multi-plane file strategy

A hatchet has two distinct horizontal planes: the flat axe body, and the tapered/curved blade. A chef's knife has three: the flat blade face, the bolster, and the spine. Build one Lightburn file per surface, not one master file.

• Each file gets its own template outline traced from the actual geometry of that surface (use a caliper, photograph at 1:1, or trace from a CAD model).
• Each surface refocuses to its own Z height before running.
• Air assist is on for both, knives produce more debris than coins.
• Run the surfaces in priority order: most expensive engraving first (the showpiece), simpler work last. If anything goes wrong, you've protected the highest-value section.

Process order on a single part

When a knife or hatchet calls for a mixed finish (engraving + black anneal + color mark), the order matters:

1. Detailed engrave first: your sharpest, lowest-error work, before any chemistry happens to the surface.
2. Anneal the targeted black areas: slow, low-power, defocused. The oxide layer needs a clean engrave-finished surface to grow on.
3. Cleaning passes over color zones: light, fast scans that lift any dust/debris settled during engraving (see below).
4. Color mark: adjust pulse width / frequency to compensate for the surface curve.
5. Cleanup: microfiber + acetone, then a light pass on the polishing wheel.

Color marking on a curved surface (MOPA advantage)

Color marking on a flat surface is hard enough, the oxide layer thickness has to be precise to within nanometers. On a curved blade, the focal distance varies across the engrave area, so a fixed setting will give you a gradient (e.g., blue at the center, drifting to purple at the edges) instead of a clean uniform color.

The MOPA advantage: you can dial in both Q-pulse width AND frequency to compensate for the focal variation. Common adjustments:

• Center of blade (in focus): pulse 200 ns, freq 60 kHz, power 25%.
• Edges (slightly out of focus): pulse 250-300 ns, freq 50 kHz, power 22%. Longer pulse compensates for lower energy density when out of focus.
• If splitting into two sublayers, set each to its own values.

Non-MOPA users (Q-switched fiber) don't have this option, pulse width is fixed, and curved surfaces are accepted as gradient or skipped entirely.

Sometimes the gradient is the goal, a blue-to-purple shimmer across a blade looks intentional. If you want it uniform, accept that you'll need to test on a scrap blade with the same curvature first.

AI vector workflow (different from AI depth maps)

For knife / hatchet engraving you want VECTOR graphics, clean shapes that fill cleanly, not depth-modulated images. The AI workflow is different from the relief-coin workflow.

1. Generate in Midjourney with vector-friendly prompts. Critical keywords: "vector", "black on white", "simple", "black and white background". These push the model toward clean shapes that image-trace well. Examples that work:
   • "Nightwolf from Mortal Kombat as a vector, black on white, wearing a bandana"
   • "A Roy Lichtenstein pop art comic book style drawing of a scary wolf running, simple black and white vector, black on white background"
2. Image trace in Illustrator (or Inkscape, free alternative). Object → Image Trace → "Black and White Logo" preset, then Expand. You now have editable paths.
3. Clean up the trace: remove orphaned points, smooth jagged edges with the Pencil tool's smooth function. AI-generated images have artifacts; spend 10 minutes here.
4. Blend with a pattern: overlap your subject with a vector scroll/damask pattern (free packs at vecteezy.com or Creative Market). Boolean intersect or trim where they meet so it reads as integrated, not stacked.
5. Drag the .ai or .svg into Lightburn as a vector layer. Set fill mode and engrave settings.

AI fill tools: automated ornamental fill for custom outlines

A newer category of AI tools is built specifically for laser workflows. Instead of generating an image from a text prompt, these tools take YOUR outline (knife blade, hatchet head, 1911 grip, custom buckle) and fill it with ornamental artwork, Baroque scrollwork, leather-tooling patterns, themed motifs. Two of the better-known options as of 2025:

Workflow (both tools)

1. Upload your outline as PNG or JPEG. NOT SVG (yet) and NO transparent background, both tools require a solid-bg raster.
2. Pick options: pattern style (e.g., Baroque floral), intricacy level, pattern symmetry (top/bottom or left/right mirror), and offset border (padding from the edge).
3. Generate for 1 credit, or use the X4 button for 4 variations at 4 credits.
4. Inspect the result. Zoom in. Save favorites with the heart icon.
5. Download the PNG.

Cutout handling

If your outline has internal holes (screw holes on a 1911 grip, pivot pins, lanyard holes), the AI recognizes them and flows artwork around them. Some users prefer to upload the outline WITHOUT cutouts and add them manually in Lightburn afterward, gives you a chance to double-check spacing before committing.

When these beat hand-tracing

• Custom-shaped parts where you want the ornamentation to flow with the silhouette (1911 grips, hatchets, knife handles, metal wallets), the AI handles the boundary fit better than dragging a generic scroll pattern.
• One-off / low-volume work where 5-30 cents per image beats 30-60 minutes of manual fill design.
• Style exploration, generate 4 variations at once, pick the best, refine.

For high-volume identical pieces, a hand-tuned vector library (vecteezy / Creative Market scrollwork packs) you've cleaned up once still wins on per-piece time.

Lightburn sublayers: organize complex jobs

When one part has three different processes (engrave + anneal + color), regular layers get unmanageable. Sublayers are a Lightburn feature for grouping related operations under a parent layer.

• Right-click a layer in the panel → Add Sublayer.
• Each sublayer has its own settings, but visually nests under the parent.
• Toggle output per sublayer when staging the multi-process run.
• Common sublayer structure for a knife: parent "Blade work" with sublayers "Engrave", "Anneal areas", "Color mark", "Cleaning pass".

Jigs for blades

• Knife: V-block jig with magnetic base for steel blades. Foam-padded clamps for non-magnetic (titanium, ceramic).
• Hatchet: flat block + a wedge or pen propped under the cutting edge to keep the engrave surface level. Yes, "whatever gets the job done" applies.
• Curved blades (chef's, hunting): laser-cut MDF cradle that matches the blade's profile. Cuts on the CO2 in 5 minutes once you have a profile.
• Always engrave the back of the part first as a test if you're going to be running unknown settings, a customer's $200 knife isn't where you want to discover the power was 5% too high.

Vocabulary note: "color engraving" vs "color marking"

The correct term is color marking, not "color engraving." The laser is not removing material, it's growing a thin oxide layer on the surface that creates color via thin-film interference. No depth, no engrave. Customers will use "color engraving" because it sounds cooler; you should know the difference and use the right term internally.

Source: Hatchet engraving walkthrough (YouTube, 60W OMTech MOPA + Lightburn), multi-plane workflow, AI vector prompts, sublayers, curved-surface color marking with MOPA pulse-width adjustment.